T-square.



G. FOBRST.

T-SQUARE.

APPLICATION FILED MAY 31, 1912.

Patented Dec. 30, 1913.

INVENTOR ATTORNEY GEORGE FOERS'I, F JERSEY CITY, NEW JERSEY.

T-S QUARE.

Specification of Letters Patent.

Patented Dec. 30, 1913.

Application filed May 31, 1912. Serial No. 700,681.

To all whom it may concern:

Be it known that I, GEORGE FoERs'r, a citizen of the United States, and resident of Jersey City, in the county of Hudson and State ofNew Jersey, have invented certain new and useful Improvements in T-Squares, of which the following is a specification.

This invention relates to T-squares and its 'object is to provide an auxiliary edge so that the edge of the square may be safely used for ruling with a writing-pen, the auxiliary edge having a tongue to be fitted in one of several grooves on the edges of the blade of the square. These and other objects and details of the invention are more fully described in the following specification, set forth in the claim and illustrated in the drawings wherein- Figure l is a plan view of the square partly in section. Fig. 2 is a cross-sectional view with the auxiliary edge fitted in the blade of the square. Fig. 3 is a perspective view of the auxiliary edge. Fig. 4 is a cross-sectional view of the blade with the auxiliary edge in the upper face. Fig. 5 is a sectional view showing the operation of the device as arranged in Fig. 4.

Squares as heretofore made have been provided with rectangular edges and have.

been unsuitable for use where writing pens are employed to rule with, and in case that the edges of the square are beveled, the construction is such as to render it imperfect for ruling with the ordinary type of ruling pen. This is because it is necessary to cut away the under corner, and the guide necessary for the edge of the pen is thereby removed so that the line is apt to be wavy and irregular. A solid edge is absolutely necessary where a, ruling pen is u ed to produce a straight line.

An ordinary T-square is represented. in Fig. 1 having the usual head and blade 11 screwed thereto. The type of square here illustrated has a blade with celluloid or similar edges 12 and one of these edges is provided with a dove-tail groove 13 on its upper face and similar grooves 14 are cut in the edges of both of these celluloid ex-' tensions. The auxiliary edge consists of a strip 15 of celluloid having a beveled edge 16, a rectangular corner 17 and a dove-tail tongue 18, the latter being adapted to fit in the groove 13 or either of the grooves 14.

The strip or edge 15 is the same length as the blade 11 and as shown in Fig. 1 it forms an addition to the right-hand celluloid extension 12 to provide a ruling edge for an ordinary drawing pad. When it is desired to remove the corner 17 from the paper the strip is removed from the groove 14 and reversed so that the beveled edge 16 is on the under side. into the groove 13 projects above the upper surface of the square and may be used as a guide for the triangle 19 shown in Fig. 5, thus removing the triangle from the surface of the paper so that it will not blot Wet lines which may be upon the paper, expediting work and preventing damage to the drawing. It is obvious that this aux iliary edge may be otherwise arranged or applied to a T-square without departing from the essential features above described.

Claim:

In a T-square, the combination with a blade having dovetail grooves in its edges and upper face, ofa strip with a dovetail edge to fit in one of the grooves and having a beveled edge to form an auxiliary ruling edge or a guide for a triangle.

Signed at New York in the county of New York and State of New York this 28th day of May A. D. 1912.

Y GEORGE FOERST.

Witnesses:

JAMES F. DUHAMEL, B. LAPNAN.

The auxiliarv edge when slid 

